In the past it has been recognized that it is desirable to provide cooling for heat generating electronic assemblies to enhance the performance and service life of such assemblies. Generally, this cooling has been provided in two ways. The first is by providing physical arrangements that promote the passive cooling of the electronic assembly. The second is by providing forced air cooling of the assemblies so as to maintain the temperature of the electronic assemblies below their maximum operating temperature.
The heat problem arises because it is desired to provide an electrical system which occupies as minimum a volume as possible and when electrical circuitry is placed into a housing which is close quartered so as to utilize a small volume, a heat problem arises. Thus, it is desired to provide for efficient dissipation of the heat. In addition, in complex electronic circuits, such as computers, it is also desired to make the system expandable. Also, it is desired to provide a system which is able to withstand high shock and vibrations for rugged commercial or government applications.
Also, electronic systems often use a plurality of circuit modules each of which performs a function, which modules are connected to form a system. Since the function performed by a particular module is often a standardized function, used throughout a particular industry, many manufacturers of electronic equipment sell "standard" modules for performing these standard functions.
One prior art approach for housing of such electronic equipment is to manufacture a sheet metal box designed specifically for each customer configuration and permanently wire the electronic modules together to provide power, ground and data signal paths. This approach involves substantial cost because a large number of different box configurations must be kept in stock to accommodate various customer configurations. Accordingly, a need has existed to provide an electronic circuit chassis which can house electronic circuit modules in various configurations without requiring a box of any type, that is also expandable according to the particular application, and which can provide passive cooling for the electronic circuit modules in the absence of forced air for convective cooling or a cold contiguous plate for conductive cooling.
Illustrative of an arrangement for passive cooling of electronic circuitry is U.S. Pat. No. 3,940,665 dated Feb. 24, 1976 entitled CHASSIS DEVICE HAVING VENTED BASE AND RADIATION MEMBER FOR SUPPORTING HEAT SOURCES. The '665 patent discloses a heat dissipation device comprising a chassis base having an air space therebelow and an H-shaped heat radiation member mounted vertically on the upper surface of the chassis base. Spaced parallel bridging portions close the openings of the H-shaped member. Electronic elements mounted on the cross piece of the H-shaped member and the bridging portions are connectively cooled by air flowing into the base and upwardly through openings that communicate with the chambers formed between the cross piece of the H-shaped member and the bridging portions.
U.S. Pat. Nos. 3,541,433 and 3,701,928 by A. R. Davis and directed to CURRENT SUPPLY APPARATUSES WITH AN INDUCTIVE WINDING AND HEAT SINK FOR SOLID STATE DEVICES and FRAMEWORK FOR SUPPORTING AIR COOLED ELECTRICAL AND ELECTRONIC EQUIPMENT disclose an alternating current controller that is adapted to be passively cooled. The alternating current controller includes a solid state controlled device section and two heat sinks in the form of two U-shaped aluminum body portions that extend vertically from the controlled device section. Each U-shaped portion is provided with vertical fins that extend perpendicularly from the outer surface of the U-shaped body portions to provide a large cooling surface and to form vertically extending channels for the passage of cooling air.
A framework for supporting these current supply apparatuses is provided by a plurality of vertical rectangular open frames interconnected at the top and bottom by tie beams and intermediately by a plurality of vertically spaced shelves. The shelves have horizontal cross members mounted on the frames and support beams mounted on the cross members in electrically isolated relation therewith. Current carrying cables in the frame, cross members and beams supply electrical current to the current control units of the '433 patent that are mounted on the connecting support beams and electrically connected thereto.
U.S. Pat. No. 4,503,484 issued on Oct. 28, 1983 for CHASSIS FOR ELECTRONIC CIRCUITRY discloses a modular chassis for electronic circuit modules in which a support frame is fabricated from two flat side panels spaced apart by four rods. The rods may be of variable length to accommodate various chassis widths. Each electronic circuit module has four slots which engage the four rods so that, when the modules are placed in the frame and the rods are in place, the modules are rigidly locked together to form a unit. Power, ground and data signals are conveyed between the modules by an internal cable which connects the modules in parallel so that only connections with external circuitry need be made through connectors in the side panels. A cover for the chassis is provided with a plurality of slots to promote cooling by natural or forced airflow of the modules.
U.S Pat. Nos. 3,648,113; 4,399,113; and 4,291,364 disclose modular electronic systems which include a plurality of electronic circuit modules that are arranged within a cabinet that is provided with a variety of apertures whereby forced airflow is introduced into the cabinet and provides desired cooling of the electronic modules before exiting in a predetermined manner.
U.S. Pat. Nos. 4,158,875; 4,386,651; and 4,148,534 disclose air cooling equipment for use in electronic systems of the type having a plurality of printed circuit wiring boards with a plurality of heat generating electronic components mounted thereon. The air cooling equipment disclosed in these patents utilize ducting that is disposed exteriorly of the frame supporting the printed circuit boards and which introduces a forced airflow into the frame through various apertures to establish multiple cooling paths for such airflow to promote cooling of the heat generating electronic components.
U.S. Pat. Nos. 3,723,823 and 3,838,777 illustrate various frames and guides for holding printed circuit boards that carry heat generating electronic components. The '823 patent provides proper alignment of a printed circuit board with an associated electrical connector after insertion of the board into the connector.
All of the aforementioned patents which disclose the state of the prior art do not teach modular segments that are adapted to be assembled into a housing for heat generating electronic modules, which housing provides passive cooling for the modules, expansion of the housing as desired, as well as providing means for electrical interconnection of the electronic modules while avoiding an undesired buildup of tolerances in assembly. Neither do such patents teach modular segments being joined together into a housing that can function satisfactorily in the hostile environment of a tank or other combat vehicle. In such environments no means of normal cooling such as forced air, cold conductive plate, or fluids are available. Further the housing may be immersed in water and be exposed to high pressure hosedowns. The housing and contained electronic modules must function in severe shock and vibration and must resist becoming a secondary projectile if the vehicle is hit by a projectile.